My question is this:
why doesn’t the truck stall when the no start condition is present. Why does it run until I turn the ignition off, then wont start after. But then after sits over night magically it starts again?
This behavior makes me think that it has to do with temperature and my wiring being compromised somewhere. Obviously in the distributor/ ignition area.
Greetings Maui_chevyk1500,
For about 15 years I was buying/driving high mileage '89-'90 Honda Civic hatchbacks
as my DD. Every single one that I bought either had, or would eventually develop the exact
same misbehavior:
* As long as it was running, it would keep running.
* If I forgot & shut it off hot between work & home, it would NOT restart until it cooled off.
* When the no-start happened, I had a gallon jug of water behind the seat, so I would open
the hood, pour the water over the lower aluminum distributor housing (distributor was installed
horizontally off of the end of the camshaft on the passenger side) ...and the car would start right up.
(And yes, I got some strange looks when I did this. :0)
The root cause of the 'always fails to start hot, yet always starts once cooled off' was a thermal-sensitive
(hot fail) electronic Ignitor module inside the distributor. This is the electronic replacement that Honda came up
with for the mechanical points way back when. (See attached.) And after the original Ignitor accumulated enough
miles/thermal cycles, this is how they would fail. NOTE: Most would choose to replace the entire
distributor with a reman for ~3x the money, but nearly always the Ignitor was all that was needed.
NOTE: The replacement units installed with thermal compound would go on to last the rest of the
life of the vehicle. Replaced several of these, 3 for me, and the rest for my friends. Never had to
replace any of them a 2nd time.
****
What does this have to do with you? You are experiencing the same thermal failure that I was, right
down to it never stalling when hot, but by the same token there's no hot restart...it has to cool off.
Given the symptoms you've observed, it seems to me that your ICM has become thermally sensitive
& you should consider replacing it. Note: I've never had a spark plug wire set give me a 'bad when hot,
good when cold' failure symptom, so at this time I wouldn't replace them for this round of troubleshooting.
By the same token, coils are funky high-voltage devices, and I always distrust them just a little. For example,
if I were to claim that this *has* to be the ICM, it will turn out to be your coil instead. :-( That's just the
way it is when it comes to trying to predict the exact behavior of ignition coils turning a steady +12V input
to multi-Kilovolt output pulses. :0)
****
To summarize, based upon all of your troubleshooting, if it were my truck I would:
* Replace the ICM with the highest quality part you can source. (Others jump in with specfic recommendations, please)
* Also have a new coil either located or in hand to try on the 2nd pass IF the ICM doesn't cure this hot no-start issue.
By the way, some will recommend replacing both ICM
and the coil. (Failing coils often make for nasty neighbors in the
electronic ignition circuit neighborhood, and can cause collateral damage on their way out.)
* Spark plug wires should only be changed if they fail the inspections that others have already noted.
* NOTE: If the new ICM comes with thermal compound, use it. Don't install it dry. (I've changed a few failing
Ignitors that had been changed before, and they were dry.) With electronics, the higher the heat, the shorter
the lifecycle. And if you have to supply the thermal compound yourself, please do, don't skip this step.
Can't sleep? Here's a nice article comparing a bunch of different thermal compounds:
ZZZZZZZZZ
Hope this answers your question on how an electronic ignition system can run hot no problem, but
at the same time won't restart until it cools off.
Best of luck. Let us know what you discover --